back to attenuators

offset attenuators:


Offset Attenuators work by mixing a fixed frequency (usually 2 or 4 mhz) in with the received signal, at
an adjustable power level. The mix causes the signal to also appear + and - 2 or 4 mhz from the original
signal. To hunt that, you need to change the frequency in your radio to match the mixed frequency.

Once you've done that, you can adjust the amount of mix being added - the less the mix, the lower the signal,
even when the signal is very strong.

While in THEORY these should be able to provide unlimited attenuation, there's usually a bit of leakage
inside the attenuator, and some "air-mixing" (or mixing through the power wires, or ground, etc) and
the best you can usually get is around 70dB of attenuation

Also, offset attenuators are usually pretty simple diode mixers, and aren't very efficient. This causes
a severe drop in the signal, which can be enough to make a signal that is already S-9 on the meter disappear
completely from the radio, until you get a little closer. This produces what looks like a donut-shaped
area around the transmitter, where the unattenuated signal is too strong to get anything but a 9, but cannot
be picked up at all through the OA, even at minimum attenuation. (full mix)


K0OV Offset Attenuator

KC9ON 3rd Planet Solar OA

misc offset attenuators

N0ZYC offset attenuator 2+4 mhz

NK0T attenuator



last updated 08/13/2023 at 10:38:42